Valve has revealed some of the specifications for its new open operating system Steam Machine prototypes. 300 lucky Steam users will be part of a beta test shipping out soon. Here are the specs of the various machines:

GPU: some units with NVidia Titan, some GTX780, some GTX760, and some GTX660

CPU: some boxes with Intel i7-4770, some i5-4570, and some i3

RAM: 16GB DDR3-1600 (CPU), 3GB GDDR5 (GPU)

Storage: 1TB/8GB Hybrid SSHD

Power Supply: Internal 450w 80Plus Gold

Dimensions: approx. 12 x 12.4 x 2.9 in high

A Valve repetitive stated that the prototype machines are high-end, high-performance boxes, built out of off-the-shelf PC parts.

"It is also fully upgradeable, allowing any user to swap out the GPU, hard drive, CPU, even the motherboard if you really want to. Apart from the custom enclosure, anyone can go and build exactly the same machine by shopping for components and assembling it themselves. And we expect that at least a few people will do just that."

These pre-built Steam Machines will soon be available in a scalable sizes but Valve wants to make it very clear that users can replace any part in the console, the operating system and even the enclosure will be fully replaceable.